Zend_Cache backend using Redis with full support for tags
This Zend_Cache backend allows you to use a Redis server as a central cache storage. Tags are fully supported without the use of TwoLevels cache so this backend is great for use on a single machine or in a cluster. Works with any Zend Framework project including all versions of Magento!
- Uses the phpredis PECL extension for best performance (requires master branch or tagged version newer than Aug 19 2011).
- Falls back to standalone PHP if phpredis isn't available using the Credis library.
- Tagging is fully supported, implemented using the Redis "set" and "hash" datatypes for efficient tag management.
- Key expiration is handled automatically by Redis.
- Supports unix socket connection for even better performance on a single machine.
- Supports configurable compression for memory savings. Can choose between gzip, lzf and snappy and can change configuration without flushing cache.
- Uses transactions to prevent race conditions between saves, cleans or removes causing unexpected results.
- Supports a configurable "auto expiry lifetime" which, if set, will be used as the TTL when the key otherwise wouldn't expire. In combination with "auto expiry refresh on load" offers a more sane cache management strategy for Magento's
- Unit tested!
- Install redis (2.4+ required)
Install phpredis (optional)
- For 2.4 support you must use the "master" branch or a tagged version newer than Aug 19, 2011.
- phpredis is optional, but it is much faster than standalone mode
- phpredis does not support setting read timeouts at the moment (see pull request #260). If you receive read errors (“read error on connection”), this might be the reason.
Install this module using modman:
modman clone https://github.com/colinmollenhour/Cm_Cache_Backend_Redis
Edit app/etc/local.xml to configure:
<!-- This is a child node of config/global --> <cache> <backend>Cm_Cache_Backend_Redis</backend> <backend_options> <server>127.0.0.1</server> <!-- or absolute path to unix socket --> <port>6379</port> <persistent></persistent> <!-- Specify unique string to enable persistent connections. E.g.: sess-db0; bugs with phpredis and php-fpm are known: https://github.com/nicolasff/phpredis/issues/70 --> <database>0</database> <!-- Redis database number; protection against accidental data loss is improved by not sharing databases --> <password></password> <!-- Specify if your Redis server requires authentication --> <force_standalone>0</force_standalone> <!-- 0 for phpredis, 1 for standalone PHP --> <connect_retries>1</connect_retries> <!-- Reduces errors due to random connection failures; a value of 1 will not retry after the first failure --> <read_timeout>10</read_timeout> <!-- Set read timeout duration; phpredis does not currently support setting read timeouts --> <automatic_cleaning_factor>0</automatic_cleaning_factor> <!-- Disabled by default --> <compress_data>1</compress_data> <!-- 0-9 for compression level, recommended: 0 or 1 --> <compress_tags>1</compress_tags> <!-- 0-9 for compression level, recommended: 0 or 1 --> <compress_threshold>20480</compress_threshold> <!-- Strings below this size will not be compressed --> <compression_lib>gzip</compression_lib> <!-- Supports gzip, lzf, lz4 (as l4z) and snappy --> <use_lua>0</use_lua> <!-- Set to 1 if Lua scripts should be used for some operations --> </backend_options> </cache> <!-- This is a child node of config/global for Magento Enterprise FPC --> <full_page_cache> <backend>Cm_Cache_Backend_Redis</backend> <backend_options> <server>127.0.0.1</server> <!-- or absolute path to unix socket --> <port>6379</port> <persistent></persistent> <!-- Specify unique string to enable persistent connections. E.g.: sess-db0; bugs with phpredis and php-fpm are known: https://github.com/nicolasff/phpredis/issues/70 --> <database>1</database> <!-- Redis database number; protection against accidental data loss is improved by not sharing databases --> <password></password> <!-- Specify if your Redis server requires authentication --> <force_standalone>0</force_standalone> <!-- 0 for phpredis, 1 for standalone PHP --> <connect_retries>1</connect_retries> <!-- Reduces errors due to random connection failures --> <lifetimelimit>57600</lifetimelimit> <!-- 16 hours of lifetime for cache record --> <compress_data>0</compress_data> <!-- DISABLE compression for EE FPC since it already uses compression --> <auto_expire_lifetime></auto_expire_lifetime> <!-- Force an expiry (Enterprise_PageCache will not set one) --> <auto_expire_refresh_on_load></auto_expire_refresh_on_load> <!-- Refresh keys when loaded (Keeps cache primed frequently requested resources) --> </backend_options> </full_page_cache>
RELATED / TUNING
- The recommended "maxmemory-policy" is "volatile-lru". All tag metadata is non-volatile so it is recommended to use key expirations unless non-volatile keys are absolutely necessary so that tag data cannot get evicted. So, be sure that the "maxmemory" is high enough to accommodate all of the tag data and non-volatile data with enough room left for the volatile key data as well.
- Automatic cleaning is optional and not recommended since it is slow and uses lots of memory.
- Occasional (e.g. once a day) garbage collection is recommended if the entire cache is infrequently cleared and automatic cleaning is not enabled. The best solution is to run a cron job which does the garbage collection. (See "Example Garbage Collection Script" below.)
- Compression will have additional CPU overhead but may be worth it for memory savings and reduced traffic. For high-latency networks it may even improve performance. Use the Magento Cache Benchmark to analyze your real-world compression performance and test your system's performance with different compression libraries.
- Monitor your redis cache statistics with my modified munin plugin.
- Enable persistent connections. Make sure that if you have multiple configurations connecting the persistent string is unique for each configuration so that "select" commands don't cause conflicts.
- Use the
stats.phpscript to inspect your cache to find oversized or wasteful cache tags.
Example Garbage Collection Script (Magento)
<?php PHP_SAPI == 'cli' or die('<h1>:P</h1>'); ini_set('memory_limit','1024M'); set_time_limit(0); error_reporting(E_ALL | E_STRICT); require_once 'app/Mage.php'; Mage::app()->getCache()->getBackend()->clean('old'); // uncomment this for Magento Enterprise Edition // Enterprise_PageCache_Model_Cache::getCacheInstance()->getFrontend()->getBackend()->clean('old');
- November 19, 2012: Added read_timeout option. (Feature only supported in standalone mode, will be supported by phpredis when pull request #260 is merged)
- October 29, 2012: Added support for persistent connections. (Thanks samm-git!)
- October 12, 2012: Improved memory usage and efficiency of garbage collection and updated recommendation.
- September 17, 2012: Added connect_retries option (default: 1) to prevent errors from random connection failures.
- July 10, 2012: Added password authentication support.
- Mar 1, 2012: Using latest Credis_Client which adds auto-reconnect for standalone mode.
- Feb 15, 2012: Changed from using separate keys for data, tags and mtime to a single hash per key.
- Nov 10, 2011: Changed from using phpredis and redisent to Credis (which wraps phpredis). Implemented pipelining.
@copyright Copyright (c) 2012 Colin Mollenhour (http://colin.mollenhour.com) This project is licensed under the "New BSD" license (see source).